Luca Blight has the prize hands down. He is one sadistic evil bastard. Suikoden 2 is highly recommended(as is Suikoden 1 plus you can use your save game in Suikoden 2 if you got all the stars in 1 to get your old hero and other perks).

Individual aside - Anyone who has played "Ur Quan Masters" aka "Star Control 2" would know of the Ur Quan Khor Ah as being the most evil race to ever exist(making even the other uber evil Ur Quan race look like saints).

The game is old but has IMO the best starship battles to date(as well as probably being one of the best overall games of any genre to date) and best of all it is now free http://sc2.sourceforge.net/ Sadly, alot of the space stage ideas found in Spore(brand new game) where done much better in SC2

My character in fable II, it has two damn big horns and a pair of glowing eyes... does that count? Well its not really that evil the worst thing I have probably done was just sacrifice the lives of my four wives all at once for a freakin weapon.